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Month: March 2017

International Date Line

One of the most important outcomes of the first circumnavigation of the world is the least recognised. Eighteen emaciated men staggered ashore after a three-year voyage around the world and discovered all their diaries and the ship’s logbook were one day in error. The seriousness of this lay in the fact that, keeping the wrong date, they may have committed the sin of eating meat on a Friday. It is not known but can be surmised that some may have confessed their sin in the church of Santa Maria de la Victoria in Seville. By coincidence, the church had the same name as their ship.
The savants of Seville, who had never left home to experience such a phenomenon, soon realised that of course, travelling always westwards around the world they had overtaken the Sun by one day. They arrived back home on a Saturday according to them when the true day was holy Friday. Who could know how many times they had sinned? How many Hail Maries must they say?
Since then, the International Date Line, or IDL, has become a plaything of politicians. Theoretically, the meridian of 180 degrees marks the line between any two dates at midnight when it is 12 noon on the Greenwich meridian. In practice the line has doglegs in it and is shifted to accommodate various political and religious whims. Ferdinand Magellan claimed the Philippines for Spain in 1521 on the basis of a different line, the line of demarcation that divided the world between Portugal and Spain. Colonisation began in 1565 and trade between the Philippines and Mexico ‘(New Spain) flourished. The Philippines operated under the Spanish calendar until 1844 when Mexico gained independence from Spain and the Philippines resumed trade with their Asian neighbours. They deleted one day from the calendar to align their time zone.
Several Pacific islands have had similar experiences. The IDL divides the world between Sunday and Monday and for 24 hours divides the world between one year and the next. New year celebrations actually roll around the world for 24 hours. Jules Verne plotted the IDL into his novel Around the World in 80 Days. He could have turned it into a thriller had he set up a race between two people circumnavigating the world in opposite directions. One would have got home in 79 days and the other in 81 days but both arrive home on the same day. Resolution of this issue could have been a plot point for the novel.
Samoa adjusted their IDL in 2011. The community of Seventh Day Adventists were divided by this issue but reached a compromise in true South Pacific style. Some decided to observe the Sabbath on the new Saturday while others opted to retain the old. What was a religious scandal in the 15th century remains so today, but I doubt Magellan is turning in his grave.

first circumnavigation 500 years on

As Portuguese explorers in the 15th century discovered new lands mapmakers naturally became busy and creative. The Pillars of Hercules are the gateway from the Mediterranean Sea to the rest of the world. In the lingering Greek mythology, Hercules had opened the gate with one slash of his sword. Another Greek god named Atlas, who took the weight of the world on his shoulders, gave his name to the Atlantic Ocean. Ferdinand Magellan opened the gate on the whole world. An atlas these days is a collection of maps that may or may not depend upon the prominence of the Mediterranean Sea.
In Magellan’s time people were just emerging from a world of myth, superstition and bigotry where fantastic stories of the gods sought to explain stuff that was not understood and human nature that was only too well understood. Ferdinand Magellan was about to change that. In a few years’ time his vision would present hard evidence to refute myths, legends and lies that heretofore had entrenched the positions of soothsayers, liars, mystics, religious freaks and kings, not to mention mathematicians.
The first circumnavigation of the world is the most significant event in human history; more important than the landing on the moon. The return of the Victoria to Spain proved beyond doubt that the world is round not flat. Unfortunately, the message has not reached teachers of mathematics. Children in school are still being told that the angles of a triangle add up to 180 degrees despite a solid body of spherical trigonometry and rocket science. The word geometry comes from two Greek words that together mean measuring the Earth, and it ain’t flat.
Nowadays our fantasies are of a different calibre than those of the ancient Greeks except for Flat Earth mathematics, or FEG. Practitioners of FEG, known as Feggers, are 500 years out of date. They have not yet discovered that the world is round not flat; dynamic not static. Politicians who don’t understand climate change, for example, resort to fantasy or alternative facts. The present age is very similar to the 15th century, with humans beginning a new age of discovery and colonialism. Will Mars be our first colony? Only a few adventurers like Magellan will boldly go to explore a new world of ideas.
The fact that our children are still being taught that the angles of a triangle add up to 180 degrees is a symptom of a deeper malaise, not even an alternative fact. There is no such thing as a straight line. You can have a loxodrome, a geodesic or an almucantar but there is no such thing as a straight line. The world is round, not flat. Think about it. Think about the word geometry 2,500 years after Euclid told us the world is flat. Euclid was peddling fake news. What are you going to do about it? Sack all your math teachers?

Like this:

The Martellus map of the world

The word Mediteranean means middle of the Earth and for many centuries that’s how it was depicted on maps. In Magellan’s time the most authoritative map of the world was that by Claudius Ptolemy, the great astronomer and geographer of second century Alexandria. No doubt Magellan knew it from his studies at the Portuguese Institute of Navigation sponsored by Prince Henry, known as the Navigator although he never went to sea.
As the Portuguese extended their empire they added to their knowledge. Map-making was a growth industry and maps of new worlds were guarded as State secrets. Magellan had access to a number of maps and globes, some more accurate than others. None of them featured the strait at the tip of South America that was later to bear his name.
The problem was not only the lack of information about distant lands but also the difficulty of rendering a spherical Earth on a flat sheet of paper. Men of science no longer doubted the world is round but the mathematics and techniques of cartography were in their infancy. Prominent Portuguese mathematician Pedro Nunes was the first to produce a formula representing a rhumb line, or loxodrome, by a straight line on a map. The importance of this is that the rhumb line is a constant compass direction as steered by a ship. Gerard Mercator extended the technique and his name now describes the familiar map of the world seen in atlases and elsewhere. The Mercator chart is still an idealised representation of the world. It suffers from severe distortion in high latitudes and the latitude or distance scale is not uniform.
A great difficulty facing medieval navigators was that maps of their day truncated or omitted the Pacific Ocean. They knew the circumference of the Earth was 360 degrees but no one knew how many miles or leagues there were in a degree of longitude. Columbus and Magellan both underestimated the circumference of the Earth by about one third. This almost led to failure of Magellan’s expedition due to death by starvation and scurvy. No one had previously imagined the vastness of the Pacific Ocean.

In 1962 an anonymous donor presented Yale University, USA, with a long lost map drawn by German cartographer Martellus in the late 15th century. It was in very poor condition but new techniques enabled researchers to peel away layers of dirt and enhance images with electronic scanners. Historians speculate Christopher Columbus may have known of this map and, if so, Magellan would have known of it too. It is thought to have been influenced by information brought back from China by Marco Polo. It is intriguing for the inclusion of considerably more detail of Asia than other maps of the time. It features an image of a castle supposed to represent Paradise. Columbus claimed to have discovered Paradise on his final voyage but historians believe that Columbus’s Paradise was the Orinoco River. The Martellus map shows a greater extent of South America than contemporaneous maps. If Magellan did know of it, this could explain his utter conviction that a strait lay at the tip of South America known as The Dragon’s Tail.